| 摘要 |
PROBLEM TO BE SOLVED: To provide an AGC circuit having a wide control range even when the circuit is driven at a low power supply voltage and to provide a differential amplifier circuit (including a comparator circuit) suitably used for the AGC circuit. SOLUTION: The AGC circuit includes: a comparator circuit 200 for comparing an output voltage with a reference voltage; a charge pump circuit 84 the operating state of which is switched on the basis of an output of the comparator circuit; averaging circuits (64, 47) for averaging a high voltage output of the charge pump circuit in terms of time; and an amplifier circuit whose amplification factor is varied with a third element 70 the impedance of which is increased / decreased with an output of the averaging circuits. COPYRIGHT: (C)2004,JPO
|
